A hot-air furnace, which is known from the market, for industrial applications, for example for the thermal oxidation of plastic fibres, has an air-delivery device which is designed as a blower and is intended to produce an airstream. The airstream is guided past a heat-transfer device, for example electrically operated heating bars or a heat-exchanger heated indirectly with thermal oil, and is heated. The heated airstream is then directed into a furnace chamber which is delimited by walls and in which the material which is to be thermally treated is located. The walls of the furnace chamber bring about a limitation of the cross-section through which the heated airstream is able to flow and thus ensure a concentrated introduction of heat into the material to be treated. The known hot-air furnace can be assembled, by the modular method of construction, from a plurality of hot-air furnace modules which may be prefabricated as subassemblies and which are connected to one another at the site at which the hot-air furnace is to be used. In certain cases, such as, in particular, in the manufacture of carbon fibres by oxidising plastic fibres, a uniform action on the material to be treated is of decisive importance, and this, in turn, presupposes precise, defined airflows. Basically, the fact is: the better the airflow distribution, the better the result.
The present invention is directed to resolving these and other matters.